Was the moderator on the official chess.com Twitch channel? If so, you can open a ticket about it.
https://support.chess.com/customer/portal/emails/new
If it is an individual streamer, the moderator may be one the channel creator approved and any issues would likely have to be taken up with that streamer.
Hi! I've been enjoying chess.com's great computer chess championship tournaments and Twich stream, but one moderator seem to not at all be suitable for the job. He writes in incoherent English which is nearly impossible to understand and he bans and timeout people for the smallest infraction such as discussing games from TCEC or even mentioning TCEC at all. He also bans anyone who question his dubious actions as a mod. I'd love for this mod to be lectured on how to use and not abuse his mod powers, or simply have him/her removed. Out of respect for the mod, I have not mentioned his Twitch handle here, but if an admin wants the username, I can send it on a PM. Cheers.